typedRoutes don't recognize parameter on rewritten url if preceded by path character

Link to the code that reproduces this issue

https://codesandbox.io/p/devbox/elastic-lucy-jfpczm?file=%2F.next%2Ftypes%2Flink.d.ts

To Reproduce

The error is in the generated types file.

Current vs. Expected behavior

If rewriting /@:username to /user/:username, I'd expect a generated type like /@${SafeSlug<T>} but instead I get /@[username].

Provide environment information

Operating System:
  Platform: darwin
  Arch: x64
  Version: Darwin Kernel Version 21.6.0: Mon Feb 19 20:24:34 PST 2024; root:xnu-8020.240.18.707.4~1/RELEASE_X86_64
  Available memory (MB): 16384
  Available CPU cores: 8
Binaries:
  Node: 22.2.0
  npm: 10.7.0
  Yarn: N/A
  pnpm: 7.33.7
Relevant Packages:
  next: 14.2.0 // There is a newer version (14.2.4) available, upgrade recommended! 
  eslint-config-next: 14.2.0
  react: 18.3.1
  react-dom: 18.3.1
  typescript: 5.4.5
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

TypeScript

Which stage(s) are affected? (Select all that apply)

next dev (local)

Additional context

No response

Run the linked CodeSandbox reproduction and inspect the generated .next/types/link.d.ts file. Compare the generated route type for a rewrite from /@:username to /user/:username with the expected parameterized form. Done means the generated type preserves the username parameter when it follows a path character.